/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */
package javax.swing.text;

/**
 * Interface to describe a structural piece of a document.  It
 * is intended to capture the spirit of an SGML element.
 *
 * @author Timothy Prinzing
 */
public interface Element {

  /**
   * Fetches the document associated with this element.
   *
   * @return the document
   */
  public Document getDocument();

  /**
   * Fetches the parent element.  If the element is a root level
   * element returns <code>null</code>.
   *
   * @return the parent element
   */
  public Element getParentElement();

  /**
   * Fetches the name of the element.  If the element is used to
   * represent some type of structure, this would be the type
   * name.
   *
   * @return the element name
   */
  public String getName();

  /**
   * Fetches the collection of attributes this element contains.
   *
   * @return the attributes for the element
   */
  public AttributeSet getAttributes();

  /**
   * Fetches the offset from the beginning of the document
   * that this element begins at.  If this element has
   * children, this will be the offset of the first child.
   * As a document position, there is an implied forward bias.
   *
   * @return the starting offset &gt;= 0 and &lt; getEndOffset();
   * @see Document
   * @see AbstractDocument
   */
  public int getStartOffset();

  /**
   * Fetches the offset from the beginning of the document
   * that this element ends at.  If this element has
   * children, this will be the end offset of the last child.
   * As a document position, there is an implied backward bias.
   * <p>
   * All the default <code>Document</code> implementations
   * descend from <code>AbstractDocument</code>.
   * <code>AbstractDocument</code> models an implied break at the end of
   * the document. As a result of this, it is possible for this to
   * return a value greater than the length of the document.
   *
   * @return the ending offset &gt; getStartOffset() and &lt;= getDocument().getLength() + 1
   * @see Document
   * @see AbstractDocument
   */
  public int getEndOffset();

  /**
   * Gets the child element index closest to the given offset.
   * The offset is specified relative to the beginning of the
   * document.  Returns <code>-1</code> if the
   * <code>Element</code> is a leaf, otherwise returns
   * the index of the <code>Element</code> that best represents
   * the given location.  Returns <code>0</code> if the location
   * is less than the start offset. Returns
   * <code>getElementCount() - 1</code> if the location is
   * greater than or equal to the end offset.
   *
   * @param offset the specified offset &gt;= 0
   * @return the element index &gt;= 0
   */
  public int getElementIndex(int offset);

  /**
   * Gets the number of child elements contained by this element.
   * If this element is a leaf, a count of zero is returned.
   *
   * @return the number of child elements &gt;= 0
   */
  public int getElementCount();

  /**
   * Fetches the child element at the given index.
   *
   * @param index the specified index &gt;= 0
   * @return the child element
   */
  public Element getElement(int index);

  /**
   * Is this element a leaf element? An element that
   * <i>may</i> have children, even if it currently
   * has no children, would return <code>false</code>.
   *
   * @return true if a leaf element else false
   */
  public boolean isLeaf();


}
